A combine harvester is typically composed of a feeder or elevator to convey crop material from the header, a threshing mechanism to mechanically thresh the grain from the plant, a cleaning system to separate the grain from the matter other than grain (MOG), a tailings return system to rethresh any unthreshed grain and return it for recleaning, and a residue handling system to distribute the MOG back to the field.
Some current combines utilize a grain pan to transport chaff and grain from the threshing mechanism to the sieves of the cleaning system. The grain pan is composed of a surface with a corrugated or saw-tooth cross-section profile which oscillates along a path generally upward and rearward with accelerations high enough to throw the chaff and grain mixture rearward in short increments until it is delivered to the sieve of the cleaning system. In some designs the grain pan is adapted with a leveling system to address side slope up to about seven degrees from level, see e.g. U.S. Pat. No. 4,344,443, which is hereby incorporated by reference.
Some combines have been fitted to address additional side slope through complicated and costly combine leveling systems, where the entire combine is tilted relative to the axles. These are costly and raise other problems, and in some cases are specialty equipment designed for specific locations and situations, such as extreme hillside farming in Washington and Oregon, for example. These combines are typically not practical for use in both level (or near level) conditions as well as their extreme slope conditions.
The grain pan system works acceptably in a majority of harvest conditions. However, when harvesting up and down hills the rate of transport of the grain/chaff mixture along the length of the grain pan is affected due to a change in the acting direction of gravitational forces on the grain/chaff with respect to the transport direction along the grain pan.
When harvesting downhill, the transport rate of the grain pan is reduced resulting in pooling of chaff and grain on the grain pan. When harvesting uphill, the transport rate of the grain pan is increased. This transition from pooling of material to increased transport can cause an overload of the cleaning system resulting in grain loss over the sieves.
An additional shortcoming of the grain pan system can be found when harvesting crop material having high moisture content which sticks to components of the cleaning system. In this condition, the corrugations of the grain pan can become entirely caked over with damp crop material. When the corrugations are caked over, the grain pan becomes a nearly flat surface with a significant reduction in grain/chaff transport rate which negatively affects the capacity of the cleaning system.
To overcome these difficulties, an auger bed can be used, which due to the driving nature of the auger helps to stabilize and control the speed of grain despite the uphill or downhill situation or other crop situations. The troughs typically employed below the auger naturally compensate for some side slope, and in some cases more so than a grain pan with a leveling system thus removing the need to address side slope.
In today's world, however, increased efficiency is a must, and although the auger system addresses minor side slope, and there is specialty equipment for extreme slopes, heretofore there is nothing to address the middle ground. Thus, there is a need to address steeper side slopes while employing auger systems, without the need for a full combine leveling system.
This application discloses such a system.